In the fields of medical, computer technology, print and energy industrials, the products are developed towards miniaturization, and the fluid transportation device included in a micro-pump, a sprayer, an inkjet head or an industrial print device therein plays a key role. As so, it is important for industry to create innovative structure of the fluid transportation device to maintain compact size and improve its performance.
Please refer to FIGS. 1A and 1B. FIGS. 1A and 1B schematically illustrate a micro-pump structure of prior art. The micro-pump structure 10 is not in action in FIG. 1A, whereas it is in action in FIG. 1B. The micro-pump structure 10 of prior art contains an inlet channel 13, a micro-actuator 15, a transportation block 14, a layer-isolating film 12, a compression chamber 111, a substrate 11 and an outlet channel 16. The compression chamber 111 is defined and formed in between the substrate 11 and the layer-isolating film 12 and mainly used for storing liquid. The volume of the compression chamber 111 would be changed by the deformation of the layer-isolating film 12.
When the micro-pump structure 10 is in action, a voltage is applied to the upper and lower poles of the micro-actuator 15 and an electric field is generated. As shown in FIG. 1B, the micro-actuator 15 is bent along the electric field, moving downwardly in the direction towards the layer-isolating film 12 and the compression chamber 111. The transportation block 14 located under the micro-actuator 15 transmits the thrust by the micro-actuator 15 to the layer-isolating film 12, such that the layer-isolating film 12 is also pressed and deformed. As a result, the volume of the compression chamber 111 is shrunken, and the liquid which has entered by the inlet channel 13 and has been stored in the compression chamber 111 is compressed by the compression chamber 111, forming an liquid flow flowing in the direction X through the outlet channel 16 to a predetermined container to achieve liquid transportation.
Please refer to FIG. 2. FIG. 2 schematically illustrates a top view of the micro-pump structure of FIG. 1A. As shown in figure, when the micro-pump structure 10 is operating, the liquid is transported in the direction Y. The inlet diffuser 17 is a tapered structure having two openings in different sizes at two ends, wherein the end with the larger opening is connected with the inlet flow passage 191, and the end with the smaller opening is connected with the compression chamber 111. Similarly, the outlet diffuser 18 is disposed in the same direction with the inlet diffuser 17, as the end thereof with larger opening is connected with the compression chamber 111, and the end thereof with the smaller opening is connected with the outlet flow passage 192. Each of the inlet diffuser 17 and the outlet diffuser 18 provides different flow resistances in two ends thereof, this characteristics plus the expansion and contraction of the volume of the compression chamber 111 can make the liquid flow at an unidirectional net flow rate, from the inlet flow passage 191 through the inlet diffuser 17 to the compression chamber 111, and through the outlet diffuser 18 to the outlet flow passage 192.
However, the above-mentioned micro-pump structure 10 does not have any solid valve and a large amount of backflow is usually happened. Therefore, it is necessary to raise the compression ratio of the compression chamber 111 to generate sufficient pressure therein that increases flow rate of the liquid. Consequently, the cost of the micro-actuator 15 is higher.
Therefore, there is a need of providing an improved fluid transportation device distinct from the prior art in order to solve the above drawbacks, which can keep certain working characteristics and flow rate in long-term utilization.